The present invention relates to methods for protecting avians against disease, in particular methods of administering vaccines to avians.
Newcastle disease (ND) causes global economic losses for the poultry industry in the range of 40 million dollars annually. The disease is caused by several different RNA viruses from the Paramyxoviridae family and symptoms range from subclinical disease to high mortality. Although vaccination programs can control ND, there are still problems due to adverse vaccine reactions and requirements for multiple vaccine administrations.
Chicks raised in the commercial poultry industry typically are vaccinated against multiple diseases. In the past, immunization for NDV generally occurred at day one and day fourteen post-hatch. More recently, in ovo injection devices have automated immunization, allowing treatment of the embryos prior to hatch. However, thus far, there has been little success with in ovo administration of live viral vaccines without a high incidence of embryo mortality. Use of a virulent NDV or other viral vaccine strain capable of producing a protective immune response with one in ovo administration would be highly advantageous. However, in ovo NDV live virus vaccination is usually toxic to the embryo, and birds that do hatch from in ovo vaccinated eggs exhibit high early mortality. Ahmad and Sharma, (1993) Avian Diseases 37:485.
Accordingly, there remains a need in the art for safe and efficacious methods of administering live pathogenic virus vaccines to birds in ovo.
The present invention is based on the discovery that interferon can be administered in conjunction with vaccines to decrease the pathogenicity thereof. In particular, interferons are effective in decreasing the pathogenic effects of live vaccines in embryonic birds. Accordingly, the present invention provides methods and pharmaceutical formulations for administering live pathogenic vaccines, preferably live pathogenic virus vaccines, to birds in ovo. The dose of interferon must be sufficient to protect the subject from the pathogenic effects of the live vaccines, but should not be so high as to prevent infection by the vaccine.
In addition, the present investigations have led to the discovery that administration of interferon in conjunction with vaccines to birds in ovo and hatchlings can overcome the inactivating (i. e., neutralizing) effects of maternal antibodies. It is well-known in the art that maternally-transmitted antibodies interfere with the efficacy of early vaccination programs in young birds. Accordingly, the present invention provides methods and pharmaceutical formulations for effectively vaccinating avian embryos and young maternal antibody positive avians.
In one embodiment, the present invention provides a method of producing protective immunity against a viral disease in an avian subject, comprising: (a) administering to an avian subject in ovo a composition comprising a vaccine comprising a live pathogenic virus; and (b) administering to the avian subject in ovo a composition comprising interferon; wherein the live pathogenic virus is administered in an amount effective to produce an immune response in the avian subject; and wherein the interferon is administered in an amount effective to (1) protect the avian subject from pathology that would occur in the absence of the interferon due to the administration of the vaccine, and (2) allow the production of a protective immune response in the avian subject.
As a further aspect, the present invention provides a method of producing protective immunity against Newcastle disease in a chicken, comprising: (a) administering to a chicken during the last half of in ovo incubation a composition comprising a vaccine comprising a live pathogenic Newcastle disease virus; and (b) administering to a chicken during the last half of in ovo incubation a composition comprising a Type I interferon; wherein the live pathogenic virus is administered in an amount effective to produce an immune response in the chicken; and wherein the Type I interferon is administered in an amount effective to (1) protect the chicken from pathology that would occur in the absence of the Type I interferon due to the administration of the vaccine, and (2) allow the production of a protective immune response in the chicken.
As a further embodiment, the present invention provides a method of reducing mortality from the administration of a live vaccine virus in ovo to an avian subject, comprising: (a) administering to an avian subject in ovo a composition comprising a vaccine comprising a live vaccine virus; and (b) administering to the avian subject in ovo a composition comprising interferon; wherein the live vaccine virus is administered in an amount effective to produce an immune response in the avian subject; and wherein the interferon is administered in an amount effective to (1) protect the avian subject from pathology that would occur in the absence of the interferon due to the administration of the vaccine, and (2) allow the production of a protective immune response in the avian subject.
As still a further aspect, the present invention provides a method of reducing disease from the administration of a live vaccine virus in ovo to an avian subject, comprising: (a) administering to an avian subject in ovo a composition comprising a vaccine comprising a live vaccine virus; and (b) administering to the avian subject in ovo a composition comprising interferon; wherein the live vaccine virus is administered in an amount effective to produce an immune response in the avian subject; and wherein the interferon is administered in an amount effective to (1) protect the avian subject from pathology that would occur in the absence of the interferon due to the administration of the vaccine, and (2) allow the production of a protective immune response in the avian subject.
As yet a further aspect, the present invention provides a method of producing protective immunity against a viral disease in an avian subject, the method comprising administering to an avian subject during the last quarter of in ovo incubation a composition comprising a vaccine comprising a live pathogenic virus and interferon, wherein the live pathogenic virus is administered in an amount effective to produce an immune response in the avian subject; and wherein the interferon is administered in an amount effective to (1) protect the avian subject from pathology that would occur in the absence of the interferon due to the administration of the vaccine, and (2) allow the production of a protective immune response in the avian subject.
Pharmaceutical formulations comprising a composition comprising a vaccine comprising a live pathogenic virus and interferon in a pharmaceutically-acceptable carrier are also an aspect of the invention.
As yet a further aspect, the present invention provides a method of producing protective immunity against a viral disease in an avian subject, comprising: (a) administering to an avian subject during the first month post-hatch a composition comprising a vaccine comprising a live pathogenic virus; and (b) administering to the avian subject during the first month post-hatch a composition comprising interferon; wherein the live pathogenic virus is administered in an amount effective to produce an immune response in the avian subject; and wherein the interferon is administered in an amount effective to (1) protect the avian subject from pathology that would occur in the absence of the interferon due to the administration of the vaccine, and (2) allow the production of a protective immune response in the avian subject.
These and other aspects of the present invention will be set forth in more detail in the description of the invention below.